Confinement and transport studies of conventional scenarios in ASDEX Upgrade
Confinement and transport studies of conventional scenarios in ASDEX Upgrade
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DOI：
10.1088/0029-5515/41/5/307
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发表时间：
2001-05
期刊：
影响因子：
3.3
通讯作者：
F. Ryter;J. Stober;A. Stäbler;G. Tardini;H. Fahrbach;O. Gruber;A. Herrmann;A. Kallenbach;M. Ka
中科院分区：
文献类型：
--
作者：
F. Ryter;J. Stober;A. Stäbler;G. Tardini;H. Fahrbach;O. Gruber;A. Herrmann;A. Kallenbach;M. Ka
在ASDEX升级中，对L模和H模的常规方案的限制研究表明，离子和电子温度分布一般受T/T临界值的限制，在这种情况下，分布是刚性的：核心温度与基座温度成正比。基于离子温度梯度驱动的湍流输运模拟结果与H？模离子实验数据吻合较好。专门针对电子回旋加热的电子传输的研究表明，电子温度分布也是僵硬的。具有Te/Te阈值的湍流候选可能是陷阱电子模和电子温度梯度驱动的不稳定性。实验得到了临界阈值(？Te/Te)c和刚度因子随温度的增加。相比之下，密度分布并不僵硬，但在这些常规情况下，形状的变化仍然温和。作为这种轮廓行为的结果，等离子体能量与基座压力成正比。整体禁闭时间随三角度的增加而增加，在高三角度时，密度接近格林沃尔德极限时，整体禁闭时间较好。在这个可操作的角落，在Q95左右，用小的II型榆树代替大的I型榆树提供了很好的限制，极大地降低了偏滤器平板上的峰值功率负荷。这一体制被认为足以用于聚变反应堆。
Confinement studies of conventional scenarios, i.e. L and H modes, in ASDEX Upgrade indicate that the ion and electron temperature profiles are generally limited by a critical value of ?T/T. When this is the case the profiles are stiff: core temperatures are proportional to pedestal temperatures. Transport simulations based on turbulence driven by an ion temperature gradient show good agreement with the ion experimental data for H?modes. Studies specifically dedicated to electron transport using electron cyclotron heating with steady state and modulated powers indicate that the electron temperature profiles are also stiff. Candidates for turbulence having a threshold in ?Te/Te may be trapped electron modes and electron temperature gradient driven instabilities. The critical threshold (?Te/Te)c and the increase of the stiffness factor with temperature are found experimentally. In contrast, the density profiles are not stiff, but the variation in shape remains moderate in these conventional scenarios. As a consequence of this profile behaviour, the plasma energy is proportional to the pedestal pressure. The global confinement time increases with triangularity and can be good at densities close to the Greenwald limit at high triangularity. In this operational corner and at q95 around 4, the replacement of large type?I ELMs by small ELMs of type?II provides good confinement with very reduced peak power load on the divertor plates. This regime is believed to be adequate for a fusion reactor.